logging - 什么是 Boost 日志 "debug output window"？

Question

我一直在浏览 Boost.Log 教程和文档，在所有示例中，它们都指的是“调试器窗口”或“调试输出窗口”，但我找不到那是什么。这是某种独立的应用程序吗？那我在哪里可以下载呢？

Answer 1

在调用 boost log 方法之前，请确保已设置接收器，这意味着您需要调用如下内容:

static void init_log(void)
{
    /* init boost log
    * 1. Add common attributes
    * 2. set log filter to trace
    */
    boost::log::add_common_attributes();
    boost::log::core::get()->add_global_attribute("Scope",
        boost::log::attributes::named_scope());
    boost::log::core::get()->set_filter(
        boost::log::trivial::severity >= boost::log::trivial::trace
    );

    /* log formatter:
    * [TimeStamp] [ThreadId] [Severity Level] [Scope] Log message
    */
    auto fmtTimeStamp = boost::log::expressions::
        format_date_time<boost::posix_time::ptime>("TimeStamp", "%Y-%m-%d %H:%M:%S.%f");
    auto fmtThreadId = boost::log::expressions::
        attr<boost::log::attributes::current_thread_id::value_type>("ThreadID");
    auto fmtSeverity = boost::log::expressions::
        attr<boost::log::trivial::severity_level>("Severity");
    auto fmtScope = boost::log::expressions::format_named_scope("Scope",
        boost::log::keywords::format = "%n(%f:%l)",
        boost::log::keywords::iteration = boost::log::expressions::reverse,
        boost::log::keywords::depth = 2);
    boost::log::formatter logFmt =
        boost::log::expressions::format("[%1%] (%2%) [%3%] [%4%] %5%")
        % fmtTimeStamp % fmtThreadId % fmtSeverity % fmtScope
        % boost::log::expressions::smessage;

    /* console sink */
    auto consoleSink = boost::log::add_console_log(std::clog);
    consoleSink->set_formatter(logFmt);

    /* fs sink */
    auto fsSink = boost::log::add_file_log(
        boost::log::keywords::file_name = "test_%Y-%m-%d_%H-%M-%S.%N.log",
        boost::log::keywords::rotation_size = 10 * 1024 * 1024,
        boost::log::keywords::min_free_space = 30 * 1024 * 1024,
        boost::log::keywords::open_mode = std::ios_base::app);
    fsSink->set_formatter(logFmt);
    fsSink->locked_backend()->auto_flush(true);
}

上面是在这里找到的一个片段: A simple sample of Boost Log

当你想记录一些东西时，你可以这样写:

BOOST_LOG_TRIVIAL(error) << "{ ERROR } Trying to bla bla bla\n";
BOOST_LOG_TRIVIAL(warning) << "{ WARNING } bla bla bla\n";

当在 Debug模式下运行时，输出将在您的调试文件夹中找到。将创建一个如下所示的文件:

test_2018-04-09_20-08-12.0.log

输出不会显示在 Visual Studio 的调试输出窗口中

如果你不想登录到一个文件而只是在调试窗口登录，那么使用这样的东西:

OutputDebugString(L"This is an output");

或者在 init_log 中添加一个额外的接收器——像这样:

/* setup logging to debugger window */
// Complete sink type
boost::shared_ptr< boost::log::core > core = boost::log::core::get();
// Create the sink. The backend requires synchronization in the frontend.
boost::shared_ptr< sink_t > sink(new sink_t());
// Set the special filter to the frontend
// in order to skip the sink when no debugger is available
sink->set_filter(boost::log::expressions::is_debugger_present());
core->add_sink(sink);

你还需要添加这个:

#include <boost/log/sinks/debug_output_backend.hpp>
#include <boost/log/sinks/event_log_backend.hpp>
#include <boost/thread/future.hpp>

typedef boost::log::sinks::synchronous_sink<boost::log::sinks::debug_output_backend> sink_t;

然后输出也将显示在调试器窗口中